Violence erupted for a seventh night across several parts of the US, just hours after President Donald Trump vowed to use military personnel to halt the protests.
"Mayors and governors must establish an overwhelming law enforcement presence until the violence has been quelled," Trump said.
"If a city or state refuses to take the actions that are necessary to defend the life and property of their residents, then I will deploy the United States military and quickly solve the problem for them."
Following his address, he walked from the White House to nearby St. John's Episcopal Church amid tight security to pose for pictures with his daughter Ivanka.
However, a few hours later, thousands of people marched through the streets of Brooklyn, shouting "justice now!", while demonstrators in Los Angeles and New York City clashed with riot police.
George Floyd, a 46-year-old African-American, was killed minutes after a policeman pinned his neck under a knee for nearly nine minutes.
A US immigration agent has shot and killed a 37-year-old woman in her car in Minneapolis on Wednesday during an immigration enforcement surge, according to local and federal officials, the latest violence in President Donald Trump's nationwide crackdown on migrants.
Israel's military said on Thursday it had carried out a targeted strike on a rocket launch site near Gaza City after identifying a failed launch, as questions mount over when the next phase of the Gaza ceasefire will begin.
Laurent Vinatier, a French researcher serving a three-year prison sentence in Russia for violating Moscow's foreign agent laws, has been freed as part of a prisoner exchange, French and Russian officials said on Thursday.
The US has seized two Venezuela-linked oil tankers in the Atlantic Ocean on Wednesday, one sailing under Russia's flag, as part of President Donald Trump's aggressive push to dictate oil flows in the Americas and force Venezuela's socialist government to become an ally.